1. Field
The present disclosure relates generally to aircraft and, in particular, to controlling movement of the aircraft. Still more particularly, the present disclosure relates to a method and apparatus for controlling the position of flight control surfaces on an aircraft to control movement of the aircraft.
2. Background
A fly-by-wire (FBW) system for an aircraft is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The flight controls in the cockpit are not connected to the flight control surfaces, engines, or other systems by cables, linkages, or other mechanical systems, as with more conventional aircraft. Instead, the movements of flight controls are converted to electronic signals transmitted by wires, optical fibers, over an air-interface, or some combination thereof.
For example, flight control computers in a fly-by-wire system use these signals to identify how to move the actuators for each flight control surface to provide the response to the movement of the flight controls. Further, the flight control computers also may perform functions without input from a pilot. For example, the flight control computers may automatically help stabilize the flight aircraft without needing input from the pilot. The flight control computers generate commands to control flight control surfaces, an engine, or other devices that control movement of the aircraft.
An aircraft with a fly-by-wire system can be lighter in weight than when using conventional controls. Also, the electronic systems in a fly-by-wire system require less maintenance as compared to mechanical systems and hydraulic systems.
Redundancy is present in fly-by-wire systems for aircraft. Multiple flight control modules in the fly-by-wire system are used to generate commands in response to receiving signals from the movement of flight control-external sensing devices. The redundancy takes into account that a flight control module may not always perform as desired.
The different components in a fly-by-wire system may communicate with each other using different types of communications architectures. For example, some fly-by-wire systems use wires that connect the components directly to each other. In this example, multiple wires can be used to provide redundant connections between the components.
In other examples, a fly-by-wire system may use a data bus, such as those used in computer systems. The data bus may reduce the amount of wiring between components. Depending on the amount of traffic on the data bus, commands may reach intended components later than desired. This situation is a timing issue in which commands sent to a component, such as an actuator control module, may not reach the component within a desired amount of time. As a result, the fly-by-wire system may not provide for a desired level of performance in the aircraft.
For example, the delays in inputs to control an engine may result in lower than desired fuel efficiency. Delays in inputs for controlling a flight control surface result in degraded human-machine handling quality and the aircraft generating greater noise than desired or lower passenger comfort.
Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues. For example, it would be desirable to have a method and apparatus that reduce issues that may be caused by inputs having delays in reaching components.